The invention relates to a safety system on track guidance lines for optionally track-guidable or road-going vehicles of the type having feeler rollers which roll along lateral transverse guide barriers of the track guidance lines, which feeler rollers can be moved between operating and non-operating position.
A safety system on track guidance lines of the above-noted type is disclosed, for example, in German Unexamined Published Patent Application (DE-OS) No. 2,739,822. In that case it is a signal operating system for the switching of block signals, for example to indicate that a vehicle is occupying a section of the track guidance line. The signal-triggering switches arranged on the trackway side in the transverse guide barriers are operated by the vehicle itself by the feeler rollers running over them.
The above mentioned literature reference does not mention optionally track-guidable or road-going vehicles whose feeler rollers can, in addition, be adjusted between, on the one hand, an operating position close to the ground, used in track-guided operation, and, on the other hand, a retracted rest position, used in road operation. Such a system is disclosed for example in German Published Unexamined Patent Application (DE-OS) No. 2,636,656.
As a rule, the feeler rollers can be moved back and forth between their operating positions and rest positions, operated under remote control and with power assistance from the driver's seat, with the result that a smooth change between track-unbound and track-bound operation is possible without stopping the vehicle. Purely manually operable feeler rollers are described in the applicant's previously unpublished patent application No. P 3538160.4-21, the adjustment of which feeler rollers between extended operating position and retracted rest position only takes place when the vehicle is stationary.
With feeler roller adjustment under remote control and with power assistance, it is possible however that, in spite of the feeler roller adjustment being triggered by the driver--for example by operation of the corresponding feeler roller extension or retraction switch on the instrument panel--the feeler roller or feeler rollers do not move into the desired final position on account of some defect or other.
When changing from track-unbound operation on normal roads to track-bound operation on track guidance lines, such a solution may have as a consequence the collision of the vehicle with the transverse guide barriers, involving an accident of greater or lesser seriousness. However, as well as technical failure, human failure is also, and particularly, conceivable, the vehicle driver simply forgetting to pivot the feeler rollers into the operating position necessary for track guidance operation. This oversight may occur both in the case of vehicles with feeler roller adjustment operated under remote control and with Power assistance, and in the case of vehicles with manual feeler roller adjustment.
An object of the invention is to provide a safety device on track guidance lines with which a satisfactorily extended state of the feeler rollers during entry into a track guidance line is automatically checked and the driver warned, if need be, in good time.
According to the invention, this object is achieved by providing feeler actuated switch control means adjacent the inlet to the track guidance line. When a dual-mode vehicle with movable feeler rollers enters the track guidance line, once the switches arranged in the transverse guide barriers have been passed by the feeler rollers, a clear signal for the rest of the track guidance line is only given by the optical display device if both switches are operated together by the feeler rollers. This is possible, however, only with contact of the feeler rollers against the transverse guide barriers, in other words with completely extended feeler rollers. The clear line signal provides the vehicle driver with reliable information as to whether the feeler rollers of his vehicle have assumed their operating position and thus that safe travelling in track-guided operation is possible, or whether there must be some defect obliging him to interrupt the journey owing to the impending danger of an accident.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.